DECIPHERING SOME UNIQUE PALEOTEMPERATURE INDICATORS IN HALITE-BEARINGSALINE LAKE DEPOSITS FROM DEATH-VALLEY, CALIFORNIA, USA

Saline lake deposits are arguably the best source of mid- to low-latit ude terrestrial paleoclimate data. Alternating elastic sediments and e vaporites of different chemical composition have long been recognized as sensitive records of changes in inflow and aridity related to a var iety of climate parameters. Several sources of paleotemperature inform ation from a halite-bearing saline lake deposit are described here - p seudomorphs of a cold-temperature evaporite mineral, homogenization te mperatures of fluid inclusions in halite, and stable-isotope compositi ons of fluid inclusions in halite. Examples of these paleoclimate data come from analysis of the lower half of a 185-m core drilled in Pleis tocene saline lake deposits at Death Valley, California. Daily and sea sonal temperature variations in saline lake waters create conditions f or the appearance and disappearance of temperature-dependent mineral p hases. In the Death Valley core, hexagonal-shaped halite crystals, pro bable pseudomorphs of the cold-temperature hydrous mineral, hydrohalit e (NaC1 . 2H(2)O), provide evidence of brine temperatures below about 0 degrees C. Homogenization temperatures of fluid inclusions in primar y halite offer an actual (not proxy) record of surface-brine temperatu res. Samples with primary fluid-inclusion textures are carefully selec ted and handled, and data are collected from single-phase aqueous-brin e inclusions chilled to nucleate vapor bubbles. Temperature variations are observable at scales of individual halite crystals (hours to days ), single halite beds (weeks to months or years), and multiples of bed s to entire facies (hundreds to tens of thousands of years). A delta(1 8)O/delta D stable isotope record from the minute quantities of brines in fluid inclusions in halite is accessible using a method recently d eveloped at the University of Calgary. The stable isotope record from the Death Valley core, a complex response to climate variables includi ng temperature, humidity, storm patterns or seasons, and inflow source s, compliments and expands the interpretation emerging from the strati graphy and homogenization temperatures.